Methyl-tertiary-butyl ether (MTBE) is well recognized as a suitable blending stock for raising octane of gasoline. The product has been in use for some time in Europe as a blending component with gasoline, and the usage of MTBE in the United States is increasing. MTBE and related ethers, blended into gasoline at a 10 to 20 percent level, increase both motor and research octane numbers by several units. The Environmental Protection Agency has sanctioned the use of MTBE in concentrations up to about 7 liquid volume percent in the United States. Due to limitations in the amount of raw material available (isobutylenes) in the United States for use in making MTBE, the U.S. gasoline pool probably will not contain more than about 3 percent at most for the time being. Nevertheless, even this is a desirable supplement to the total gasoline available.
Addition of even up to 10 percent of such ether to gasoline reportedly does not significantly affect any properties of the resulting blend except increasing octane.
MTBE is produced by reacting isobutylene with methanol, resulting in the formation of methyl-tertiary-butyl ether. The reaction normally is conducted in liquid phase and relatively mild conditions. While mixed butylene streams can be employed, only the tertiary olefin, isobutylene, reacts at the conditions employed. A catalyst normally is used, an ion exchange resin. The isobutylene component can be obtained from various sources, such as naphtha cracking, catalytic cracking, and so on. Refer Hydrocarbon Processing, December, 1979, pages 109 and following; and The Oil and Gas Journal, Apr. 9, 1979, pages 149 and following.